1 /*
2 * Copyright 2013 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "Sample.h"
9 #include "SkCanvas.h"
10 #include "SkPaint.h"
11 #include "SkPath.h"
12 #include "SkRandom.h"
13
14 // Generates y values for the chart plots.
gen_data(SkScalar yAvg,SkScalar ySpread,int count,SkTDArray<SkScalar> * dataPts)15 static void gen_data(SkScalar yAvg, SkScalar ySpread, int count, SkTDArray<SkScalar>* dataPts) {
16 dataPts->setCount(count);
17 static SkRandom gRandom;
18 for (int i = 0; i < count; ++i) {
19 (*dataPts)[i] = gRandom.nextRangeScalar(yAvg - SkScalarHalf(ySpread),
20 yAvg + SkScalarHalf(ySpread));
21 }
22 }
23
24 // Generates a path to stroke along the top of each plot and a fill path for the area below each
25 // plot. The fill path is bounded below by the bottomData plot points or a horizontal line at
26 // yBase if bottomData == nullptr.
27 // The plots are animated by rotating the data points by leftShift.
gen_paths(const SkTDArray<SkScalar> & topData,const SkTDArray<SkScalar> * bottomData,SkScalar yBase,SkScalar xLeft,SkScalar xDelta,int leftShift,SkPath * plot,SkPath * fill)28 static void gen_paths(const SkTDArray<SkScalar>& topData,
29 const SkTDArray<SkScalar>* bottomData,
30 SkScalar yBase,
31 SkScalar xLeft, SkScalar xDelta,
32 int leftShift,
33 SkPath* plot, SkPath* fill) {
34 plot->rewind();
35 fill->rewind();
36 plot->incReserve(topData.count());
37 if (nullptr == bottomData) {
38 fill->incReserve(topData.count() + 2);
39 } else {
40 fill->incReserve(2 * topData.count());
41 }
42
43 leftShift %= topData.count();
44 SkScalar x = xLeft;
45
46 // Account for the leftShift using two loops
47 int shiftToEndCount = topData.count() - leftShift;
48 plot->moveTo(x, topData[leftShift]);
49 fill->moveTo(x, topData[leftShift]);
50
51 for (int i = 1; i < shiftToEndCount; ++i) {
52 plot->lineTo(x, topData[i + leftShift]);
53 fill->lineTo(x, topData[i + leftShift]);
54 x += xDelta;
55 }
56
57 for (int i = 0; i < leftShift; ++i) {
58 plot->lineTo(x, topData[i]);
59 fill->lineTo(x, topData[i]);
60 x += xDelta;
61 }
62
63 if (bottomData) {
64 SkASSERT(bottomData->count() == topData.count());
65 // iterate backwards over the previous graph's data to generate the bottom of the filled
66 // area (and account for leftShift).
67 for (int i = 0; i < leftShift; ++i) {
68 x -= xDelta;
69 fill->lineTo(x, (*bottomData)[leftShift - 1 - i]);
70 }
71 for (int i = 0; i < shiftToEndCount; ++i) {
72 x -= xDelta;
73 fill->lineTo(x, (*bottomData)[bottomData->count() - 1 - i]);
74 }
75 } else {
76 fill->lineTo(x - xDelta, yBase);
77 fill->lineTo(xLeft, yBase);
78 }
79 }
80
81 // A set of scrolling line plots with the area between each plot filled. Stresses out GPU path
82 // filling
83 class ChartView : public Sample {
84 public:
ChartView()85 ChartView() {
86 fShift = 0;
87 fSize.set(-1, -1);
88 }
89
90 protected:
onQuery(Sample::Event * evt)91 bool onQuery(Sample::Event* evt) override {
92 if (Sample::TitleQ(*evt)) {
93 Sample::TitleR(evt, "Chart");
94 return true;
95 }
96 return this->INHERITED::onQuery(evt);
97 }
98
onDrawContent(SkCanvas * canvas)99 void onDrawContent(SkCanvas* canvas) override {
100 bool sizeChanged = false;
101 if (canvas->getBaseLayerSize() != fSize) {
102 fSize = canvas->getBaseLayerSize();
103 sizeChanged = true;
104 }
105
106 SkScalar ySpread = SkIntToScalar(fSize.fHeight / 20);
107
108 SkScalar height = SkIntToScalar(fSize.fHeight);
109
110 if (sizeChanged) {
111 int dataPointCount = SkMax32(fSize.fWidth / kPixelsPerTick + 1, 2);
112
113 for (int i = 0; i < kNumGraphs; ++i) {
114 SkScalar y = (kNumGraphs - i) * (height - ySpread) / (kNumGraphs + 1);
115 fData[i].reset();
116 gen_data(y, ySpread, dataPointCount, fData + i);
117 }
118 }
119
120 canvas->clear(0xFFE0F0E0);
121
122 static SkRandom colorRand;
123 static SkColor gColors[kNumGraphs] = { 0x0 };
124 if (0 == gColors[0]) {
125 for (int i = 0; i < kNumGraphs; ++i) {
126 gColors[i] = colorRand.nextU() | 0xff000000;
127 }
128 }
129
130 SkPath plotPath;
131 SkPath fillPath;
132
133 static const SkScalar kStrokeWidth = SkIntToScalar(2);
134 SkPaint plotPaint;
135 SkPaint fillPaint;
136 plotPaint.setAntiAlias(true);
137 plotPaint.setStyle(SkPaint::kStroke_Style);
138 plotPaint.setStrokeWidth(kStrokeWidth);
139 plotPaint.setStrokeCap(SkPaint::kRound_Cap);
140 plotPaint.setStrokeJoin(SkPaint::kRound_Join);
141 fillPaint.setAntiAlias(true);
142 fillPaint.setStyle(SkPaint::kFill_Style);
143
144 SkTDArray<SkScalar>* prevData = nullptr;
145 for (int i = 0; i < kNumGraphs; ++i) {
146 gen_paths(fData[i],
147 prevData,
148 height,
149 0,
150 SkIntToScalar(kPixelsPerTick),
151 fShift,
152 &plotPath,
153 &fillPath);
154
155 // Make the fills partially transparent
156 fillPaint.setColor((gColors[i] & 0x00ffffff) | 0x80000000);
157 canvas->drawPath(fillPath, fillPaint);
158
159 plotPaint.setColor(gColors[i]);
160 canvas->drawPath(plotPath, plotPaint);
161
162 prevData = fData + i;
163 }
164
165 fShift += kShiftPerFrame;
166 }
167
168 private:
169 enum {
170 kNumGraphs = 5,
171 kPixelsPerTick = 3,
172 kShiftPerFrame = 1,
173 };
174 int fShift;
175 SkISize fSize;
176 SkTDArray<SkScalar> fData[kNumGraphs];
177 typedef Sample INHERITED;
178 };
179
180 //////////////////////////////////////////////////////////////////////////////
181
182 DEF_SAMPLE( return new ChartView(); )
183